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Advances in Experimental Medicine and... 2020Calcium (Ca) is a universal signaling ion, whose major informational role shaped the evolution of signaling pathways, enabling cellular communications and responsiveness... (Review)
Review
Calcium (Ca) is a universal signaling ion, whose major informational role shaped the evolution of signaling pathways, enabling cellular communications and responsiveness to both the intracellular and extracellular environments. Elaborate Ca regulatory networks have been well characterized in eukaryotic cells, where Ca regulates a number of essential cellular processes, ranging from cell division, transport and motility, to apoptosis and pathogenesis. However, in bacteria, the knowledge on Ca signaling is still fragmentary. This is complicated by the large variability of environments that bacteria inhabit with diverse levels of Ca. Yet another complication arises when bacterial pathogens invade a host and become exposed to different levels of Ca that (1) are tightly regulated by the host, (2) control host defenses including immune responses to bacterial infections, and (3) become impaired during diseases. The invading pathogens evolved to recognize and respond to the host Ca, triggering the molecular mechanisms of adhesion, biofilm formation, host cellular damage, and host-defense resistance, processes enabling the development of persistent infections. In this review, we discuss: (1) Ca as a determinant of a host environment for invading bacterial pathogens, (2) the role of Ca in regulating main events of host colonization and bacterial virulence, and (3) the molecular mechanisms of Ca signaling in bacterial pathogens.
Topics: Bacteria; Bacterial Infections; Calcium; Host Microbial Interactions; Humans; Virulence
PubMed: 31646536
DOI: 10.1007/978-3-030-12457-1_33 -
Molecular Genetics and Genomics : MGG Nov 2022The current pandemic (COVID-19) has made evident the need to approach pathogenicity from a deeper and more systematic perspective that might lead to methodologies to...
The current pandemic (COVID-19) has made evident the need to approach pathogenicity from a deeper and more systematic perspective that might lead to methodologies to quickly predict new strains of microbes that could be pathogenic to humans. Here we propose as a solution a general and principled definition of pathogenicity that can be practically implemented in operational ways in a framework for characterizing and assessing the (degree of) potential pathogenicity of a microbe to a given host (e.g., a human individual) just based on DNA biomarkers, and to the point of predicting its impact on a host a priori to a meaningful degree of accuracy. The definition is based on basic biochemistry, the Gibbs free Energy of duplex formation between oligonucleotides and some deep structural properties of DNA revealed by an approximation with certain properties. We propose two operational tests based on the nearest neighbor (NN) model of the Gibbs Energy and an approximating metric (the h-distance.) Quality assessments demonstrate that these tests predict pathogenicity with an accuracy of over 80%, and sensitivity and specificity over 90%. Other tests obtained by training machine learning models on deep features extracted from DNA sequences yield scores of 90% for accuracy, 100% for sensitivity and 80% for specificity. These results hint towards the possibility of an operational, objective, and general conceptual framework for prior identification of pathogens and their impact without the cost of death or sickness in a host (e.g., humans.) Consequently, a reasonable prediction of possible pathogens might pave the way to eventually transform the way we handle and prepare for future pandemic events and mitigate the adverse impact on human health, while reducing the number of clinical trials to obtain similar results.
Topics: Humans; Virulence; COVID-19; Oligonucleotides; DNA; Biomarkers
PubMed: 36125534
DOI: 10.1007/s00438-022-01951-w -
Frontiers in Cellular and Infection... 2019During infection, bacterial pathogens successfully sense, respond and adapt to a myriad of harsh environments presented by the mammalian host. This exquisite level of... (Review)
Review
During infection, bacterial pathogens successfully sense, respond and adapt to a myriad of harsh environments presented by the mammalian host. This exquisite level of adaptation requires a robust modulation of their physiological and metabolic features. Additionally, virulence determinants, which include host invasion, colonization and survival despite the host's immune responses and antimicrobial therapy, must be optimally orchestrated by the pathogen at all times during infection. This can only be achieved by tight coordination of gene expression. A large body of evidence implicate the prolific roles played by bacterial regulatory RNAs in mediating gene expression both at the transcriptional and post-transcriptional levels. This review describes mechanistic and regulatory aspects of bacterial regulatory RNAs and highlights how these molecules increase virulence efficiency in human pathogens. As illustrative examples, , the uropathogenic strain of , and have been selected.
Topics: Animals; Bacterial Infections; Bacterial Physiological Phenomena; Gene Expression Regulation, Bacterial; Host-Pathogen Interactions; Humans; RNA, Bacterial; Species Specificity; Virulence; Virulence Factors
PubMed: 31649894
DOI: 10.3389/fcimb.2019.00337 -
BMC Microbiology Aug 2023Vascular system is affected by diseases that can seriously damage plant health by inducing browning and death of branches. This study aimed to identify and analyze the...
BACKGROUND
Vascular system is affected by diseases that can seriously damage plant health by inducing browning and death of branches. This study aimed to identify and analyze the pathogenicity of Fusarium spp. isolates obtained from diseased peach branches in several peach-producing areas of China.
RESULTS
We obtained and confirmed nine Fusarium isolates based on morphological and molecular characteristics. Phylogenetic relationships using a combination of rDNA-internal transcribed spacer (ITS), elongation factor (EF)-1α, and mitochondrial small subunit (mtSSU) gene sequences were analyzed. GJH-Z1, GJH-6, and GJH-1 were identified as F. avenaceum; HYR-Z3, and ZLZT-6 as F. concentricum, HH-2020-G2, and HYTZ-4 as F. solani, GG-2020-1 as F. asiaticum, SYGZ-1 as F. equiseti. Through acupuncture comparison, the pathogenicity of F. equiseti (SYGZ-1) was highest amongst nine strains. Meanwhile, F. concentricum (HYR-Z3 and ZLZT-6), and F. solaini (HYTZ-4) had a higher level of pathogenicity as revealed by impregnation.
CONCLUSIONS
Our study shed light on the findings that Fusarium spp. can inflict vascular bundle browning of peach plants. Our results will extend the understanding of pathogenic diseases in China's peach industry.
Topics: Fusarium; Prunus persica; Phylogeny; Virulence; China
PubMed: 37550608
DOI: 10.1186/s12866-023-02958-y -
Nature Microbiology Jan 2020Microbial pathogens possess an arsenal of strategies to invade their hosts, evade immune defences and promote infection. In particular, bacteria use virulence factors,... (Review)
Review
Microbial pathogens possess an arsenal of strategies to invade their hosts, evade immune defences and promote infection. In particular, bacteria use virulence factors, such as secreted toxins and effector proteins, to manipulate host cellular processes and establish a replicative niche. Survival of eukaryotic organisms in the face of such challenge requires host mechanisms to detect and counteract these pathogen-specific virulence strategies. In this Review, we focus on effector-triggered immunity (ETI) in metazoan organisms as a mechanism for pathogen sensing and distinguishing pathogenic from non-pathogenic microorganisms. For the purposes of this Review, we adopt the concept of ETI formulated originally in the context of plant pathogens and their hosts, wherein specific host proteins 'guard' central cellular processes and trigger inflammatory responses following pathogen-driven disruption of these processes. While molecular mechanisms of ETI are well-described in plants, our understanding of functionally analogous mechanisms in metazoans is still emerging. In this Review, we present an overview of ETI in metazoans and discuss recently described cellular processes that are guarded by the host. Although all pathogens manipulate host pathways, we focus primarily on bacterial pathogens and highlight pathways of effector-triggered immune defence that sense disruption of core cellular processes by pathogens. Finally, we discuss recent developments in our understanding of how pathogens can evade ETI to overcome these host adaptations.
Topics: Animals; Bacteria; Bacterial Infections; Immune Evasion; Immunity, Innate; Inflammasomes; Receptors, Pattern Recognition; Signal Transduction; Virulence; Virulence Factors
PubMed: 31857733
DOI: 10.1038/s41564-019-0623-2 -
Molecular Plant Pathology May 2008The term virulence has a conflicting history among plant pathologists. Here we define virulence as the degree of damage caused to a host by parasite infection, assumed... (Review)
Review
The term virulence has a conflicting history among plant pathologists. Here we define virulence as the degree of damage caused to a host by parasite infection, assumed to be negatively correlated with host fitness, and pathogenicity the qualitative capacity of a parasite to infect and cause disease on a host. Selection may act on both virulence and pathogenicity, and their change in parasite populations can drive parasite evolution and host-parasite co-evolution. Extensive theoretical analyses of the factors that shape the evolution of pathogenicity and virulence have been reported in last three decades. Experimental work has not followed the path of theoretical analyses. Plant pathologists have shown greater interest in pathogenicity than in virulence, and our understanding of the molecular basis of pathogenicity has increased enormously. However, little is known regarding the molecular basis of virulence. It has been proposed that the mechanisms of recognition of parasites by hosts will have consequences for the evolution of pathogenicity, but much experimental work is still needed to test these hypotheses. Much theoretical work has been based on evidence from cellular plant pathogens. We review here the current experimental and observational evidence on which to test theoretical hypotheses or conjectures. We compare evidence from viruses and cellular pathogens, mostly fungi and oomycetes, which differ widely in genomic complexity and in parasitism. Data on the evolution of pathogenicity and virulence from viruses and fungi show important differences, and their comparison is necessary to establish the generality of hypotheses on pathogenicity and virulence evolution.
Topics: Animals; Evolution, Molecular; Fungi; Host-Pathogen Interactions; Plant Diseases; Plant Viruses; Plants; Virulence
PubMed: 18705877
DOI: 10.1111/j.1364-3703.2007.00460.x -
Microbiology Spectrum Oct 2014Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and... (Review)
Review
Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and surgical wound infections among hospitalized patients. These infections have become particularly problematic because many of the species causing them have become highly resistant to antibiotics. The role of mobile genetic elements, such as plasmids, in the dissemination of antibiotic resistance among Gram-positive bacteria has been well studied; less well understood is the role of mobile elements in the evolution and spread of virulence traits among these pathogens. While these organisms are leading agents of infection, they are also prominent members of the human commensal ecology. It appears that these bacteria are able to take advantage of the intimate association between host and commensal, via virulence traits that exacerbate infection and cause disease. However, evolution into an obligate pathogen has not occurred, presumably because it would lead to rejection of pathogenic organisms from the host ecology. Instead, in organisms that exist as both commensal and pathogen, selection has favored the development of mechanisms for variability. As a result, many virulence traits are localized on mobile genetic elements, such as virulence plasmids and pathogenicity islands. Virulence traits may occur within a minority of isolates of a given species, but these minority populations have nonetheless emerged as a leading problem in infectious disease. This chapter reviews virulence plasmids in nonsporulating Gram-positive bacteria, and examines their contribution to disease pathogenesis.
Topics: Animals; Bacterial Infections; Gene Transfer, Horizontal; Gram-Positive Bacteria; Humans; Plasmids; Virulence; Virulence Factors
PubMed: 25544937
DOI: 10.1128/microbiolspec.PLAS-0002-2013 -
Fungal Genetics and Biology : FG & B Sep 2017Fungi, like other organisms, actively sense the environmental light conditions in order to drive adaptive responses, including protective mechanisms against the... (Review)
Review
Fungi, like other organisms, actively sense the environmental light conditions in order to drive adaptive responses, including protective mechanisms against the light-associated stresses, and to regulate development. Ecological niches are characterized by different light regimes, for instance light is absent underground, and light spectra from the sunlight are changed underwater or under the canopy of foliage due to the absorption of distinct wavelengths by bacterial, algal and plant pigments. Considering the fact that fungi have evolved to adapt to their habitats, the complexities of their 'visual' systems may vary significantly. Fungi that are pathogenic on plants experience a special light regime because the host always seeks the optimum light conditions for photosynthesis - and the pathogen has to cope with this environment. When the pathogen lives under the canopy and is indirectly exposed to sunlight, it is confronted with an altered light spectrum enriched for green and far-red light. Botrytis cinerea, the gray mold fungus, is an aggressive plant pathogen mainly infecting the above-ground parts of the plant. As outlined in this review, the Leotiomycete maintains a highly sophisticated light signaling machinery, integrating (near)-UV, blue, green, red and far-red light signals by use of at least eleven potential photoreceptors to trigger a variety of responses, i.e. protection (pigmentation, enzymatic systems), morphogenesis (conidiation, apothecial development), entrainment of a circadian clock, and positive and negative tropism of multicellular (conidiophores, apothecia) and unicellular structures (conidial germ tubes). In that sense, 'looking through the eyes' of this plant pathogen will expand our knowledge of fungal photobiology.
Topics: Botrytis; Circadian Clocks; Cryptochromes; Light; Photoreceptors, Microbial; Phototropism; Plant Components, Aerial; Signal Transduction; Virulence
PubMed: 28648816
DOI: 10.1016/j.fgb.2017.06.002 -
Molecular Plant Pathology Oct 2016Most classical plant hormones are also produced by pathogenic and symbiotic fungi. The way in which these molecules favour the invasion of plant tissues and the... (Review)
Review
Most classical plant hormones are also produced by pathogenic and symbiotic fungi. The way in which these molecules favour the invasion of plant tissues and the development of fungi inside plant tissues is still largely unknown. In this review, we examine the different roles of such hormone production by pathogenic fungi. Converging evidence suggests that these fungal-derived molecules have potentially two modes of action: (i) they may perturb plant processes, either positively or negatively, to favour invasion and nutrient uptake; and (ii) they may also act as signals for the fungi themselves to engage appropriate developmental and physiological processes adapted to their environment. Indirect evidence suggests that abscisic acid, gibberellic acid and ethylene produced by fungi participate in pathogenicity. There is now evidence that auxin and cytokinins could be positive regulators required for virulence. Further research should establish whether or not fungal-derived hormones act like other fungal effectors.
Topics: Fungi; Host-Pathogen Interactions; Plant Growth Regulators; Plants; Virulence; Virulence Factors
PubMed: 26950404
DOI: 10.1111/mpp.12393 -
International Journal of Molecular... Aug 2023is a devastating fungal pathogen that causes severe crop losses worldwide. It is of vital importance to understand its pathogenic mechanism for disease control. Through...
is a devastating fungal pathogen that causes severe crop losses worldwide. It is of vital importance to understand its pathogenic mechanism for disease control. Through a forward genetic screen combined with next-generation sequencing, a putative protein kinase, Cak1, was found to be involved in the growth and pathogenicity of . Knockout and complementation experiments confirmed that deletions in caused defects in mycelium and sclerotia development, as well as appressoria formation and host penetration, leading to complete loss of virulence. These findings suggest that Cak1 is essential for the growth, development, and pathogenicity of . Therefore, Cak1 could serve as a potential target for the control of infection through host-induced gene silencing (HIGS), which could increase crop resistance to the pathogen.
Topics: Virulence; Ascomycota; Gene Silencing; High-Throughput Nucleotide Sequencing
PubMed: 37628791
DOI: 10.3390/ijms241612610